1. Field of the Invention
The present invention relates to a method and apparatus suitable for mass production of uniform magnetic head sliders.
2. Description of the Related Art
In a manufacturing process for a magnetic head slider, for example, a magnetic head thin-film is formed on a substrate, and is thereafter subjected to lapping. In this lapping, the heights of a magnetic resistance layer and a gap in the magnetic head thin-film are made constant. The heights of the magnetic resistance layer and the gap are required to have a high accuracy on the order of submicrons. Accordingly, a high working accuracy is required in a lapping apparatus for lapping a row bar as a workpiece.
A conventional magnetic head manufacturing process includes the steps of cutting a wafer to prepare a row bar having a plurality of magnetic head elements arranged in a row, and bonding the row bar to a row tool. This bonding step is carried out by using a bonding apparatus disclosed in Japanese Patent Laid-open No. 10-277469, for example. This bonding apparatus is composed of an adhesive applying mechanism for applying an adhesive in a given amount to the row tool, a rinking mechanism for uniforming the adhesive between the row tool and the row bar, and a presser mechanism for accelerating the curing of the adhesive in the condition where the row tool and the row bar are positioned. In Japanese Patent Laid-open No. 6-349222, there is proposed a method including the steps of bonding a plurality of row bars to a row tool, and thereafter cutting off one of the row bars. However, in this conventional method, the rigidity of the workpiece is reduced with the repetition of the cutting step, causing an adverse effect on the straightness of the workpiece.
As mentioned above, the magnetic head slider is subjected to lapping so that the height of the magnetic resistance film becomes constant. However, the row bar is very thin such that its thickness is about 0.3 mm. Accordingly, it is difficult to directly lap the row bar by the lapping apparatus, so that the row bar bonded to the row tool is pressed on a lap plate in lapping. During the lapping operation, a resistance in an electrical lapping guide element (ELG element) integrally formed in the row bar is always measured as known in U.S. Pat. No. 5,023,991 and Japanese Patent Laid-open No. 5-123960, for example.
Then, whether or not the height of the magnetic resistance film of each magnetic head element in the row bar has become a target height is detected according to the measured resistance. When it is detected that the magnetic resistance film has been lapped to the target height, according to the measured resistance, the lapping operation is ended. Thereafter, the lapped surface of the row bar is worked to form flying surfaces of a plurality of magnetic head sliders. Then, the row bar is cut into parts having the plurality of magnetic head sliders. Finally, the row tool is heated to melt the adhesive bonding the row bar to the row tool, thereby produce the individual magnetic head sliders.
In this manner, a wafer is first cut to prepare a row bar having a plurality of magnetic head elements arranged in a row, and the row bar is then lapped to thereby allow simultaneous lapping of the magnetic resistance films of the plural magnetic head elements. However, there are variations on the order of submicrons in the height of the magnetic resistance film between the individual magnetic head elements in the row bar, according to the film forming accuracy of the magnetic resistance film or the bonding accuracy of the row bar to the row tool. Accordingly, such variations must be corrected in lapping the row bar, so as to mass-produce magnetic head sliders having uniform characteristics.
Various methods have conventionally been proposed to correct the variations on the order of submicrons in lapping. For example, U.S. Pat. No. 5,607,346 has proposed a method including the steps of forming a plurality of holes in a row tool and respectively applying forces of actuators through the holes to the row tool. However, each actuator is required to have a capability of applying a relatively large force, so as to obtain a desired pressure distribution. Accordingly, it is difficult to manufacture such actuators for applying operational forces to the row tool at multiple points, so that the spacing of these multiple points (holes) cannot be so decreased. As a result, it is difficult to improve the working (lapping) accuracy of the row bar.
It is therefore an object of the present invention to provide a bonding method and apparatus which can prevent the warpage and/or distortion of a row bar bonded to a row tool.
It is another object of the present invention to provide a lapping apparatus, row tool, and lapping method suitable for improvement in working accuracy.
In accordance with an aspect of the present invention, there is provided a method comprising the steps of cutting a wafer to prepare a row block having a plurality of head elements arranged in a matrix; bonding a plate member to one side surface of said row block; bonding a row tool to another side surface of said row block bonded to said plate member opposite to said one side surface; and cutting said row block to prepare a row bar bonded to said row tool and having a row of said head elements.
Preferably, said plate member comprises a dummy wafer. Preferably, the above method further comprises the steps of bonding another row tool to a cut surface of said row block remaining after said cutting step; and repeating said cutting step for said remaining row block.
In accordance with another aspect of the present invention, there is provided an apparatus for bonding a row block having a plurality of head elements arranged in a matrix to a plate member, comprising a carrier block having a positioning pin for positioning said row block; a first preheating assembly for preheating said plate member; a second preheating assembly for preheating said row block; a rail assembly having a first block for mounting said plate member and a second block for substantially vertically holding said plate member in cooperation with said first block; an adhesive applying assembly for applying an adhesive to one side surface of said plate member held in said rail assembly; a rinking assembly having a rinking base for mounting said carrier block, a clamper for clamping said plate member mounted on said carrier block, a drive mechanism for reciprocating said clamper, and a first presser block for pressing said row block mounted on said carrier block against said one side surface of said plate member; and a bonding assembly having a bonding base for mounting said carrier block, a positioning block for positioning said plate member and said row block mounted on said carrier block, a second presser block for pressing said row block against said one side surface of said plate member, and an air nozzle for spraying air to a bonding portion between said row block and said plate member.
Preferably, said carrier block is in L-shaped configuration and has a hole for vacuum suction. The first preheating assembly has a first heating block having a plurality of grooves each for receiving said plate member, and a first heater for heating said first heating block. The second preheating assembly has a second heating block for placing said row block, and a second heater for heating said second heating block.
Preferably, said first block of said rail assembly is in L-shaped configuration, and said rail assembly further has a third block for pushing one end of said plate member mounted on said L-shaped first block, and a third heater for heating said first block. The adhesive applying assembly has a syringe for dispensing said adhesive, a temperature control block for heating said syringe to a given temperature, a cylinder for vertically moving said syringe, and a robot for moving said syringe along said rail assembly.
Preferably, said drive mechanism of said rinking assembly has a motor, a rinking stroke adjusting disc mounted on said motor, and a connecting rod for connecting said rinking stroke adjusting disc and said damper and having a connecting end offset from an output shaft of said motor.
In accordance with a further aspect of the present invention, there is provided an apparatus for lapping a row bar having a plurality of head elements arranged in a row, comprising a lap plate for providing a lapping surface; a row tool having an upper surface, a lower surface to which said row bar is bonded, and a plurality of bend cells formed by a plurality of slits; an air plate fixed to said upper surface of said row tool and having a plurality of holes respectively corresponding to said plurality of bend cells; a presser mechanism for pressing said row bar bonded to said lower surface of said row tool against said lapping surface of said lap plate; a plurality of electro-pneumatic conversion regulators respectively connected to said plurality of holes of said air plate; and a compressed air source connected to said plurality of electro-pneumatic conversion regulators.
The row tool further has a parallel spring mechanism and a pair of fixed cells formed on the opposite sides of said bend cells, each of said fixed cells having a width larger than that of each of said bend cells. Preferably, the upper surface of said row tool and the lower surface of said air plate are polished so as to have a flatness of 3 xcexcm or less. Preferably, said presser mechanism has a lap head for pressing said row bar on said lapping surface by a self-weight, and a pneumatic cylinder for adjustably applying a lapping pressure to said lap head.
In accordance with a still further aspect of the present invention, there is provided a method of lapping a row bar having a plurality of head elements arranged in a row, comprising the steps of providing a lapping surface by a lap plate; pressing said row bar bonded to a lower surface of a row tool having a plurality of bend cells formed by a plurality of slits, against said lapping surface; and applying individually adjustable air pressures to said bend cells, respectively, through an air plate fixed to an upper surface of said row tool and having a plurality of holes respectively corresponding to said bend cells; whereby said row bar is displaced at multiple points in lapping.
In accordance with a still further aspect of the present invention, there is provided a row tool to which a row bar having a plurality of head elements arranged in a row is adapted to be bonded, comprising a plurality of bend cells formed by a plurality of slits; a pair of fixed cells formed on the opposite sides of said bend cells, each of said fixed cells having a width larger than that of each of said bend cells; and a parallel spring mechanism.
In accordance with a still further aspect of the present invention, there is provided a row tool assembly comprising a row tool having an upper surface, a plurality of bend cells formed by a plurality of slits, a parallel spring mechanism, an insert hole extending horizontally, and a plurality of first holes communicating with said insert hole and opening to said upper surface; an air lead frame inserted in said insert hole of said row tool and having a plurality of air reservoirs respectively communicating with said first holes of said row tool; and an air plate fixed to said upper surface of said row tool and having a plurality of second holes respectively communicating with said first holes of said row tool.
The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claims with reference to the attached drawings showing some preferred embodiments of the invention.